1. Field of the Invention
The present invention relates to a manufacturing system and apparatus capable of performing a high-precision processing by measuring a work processed by a NC machine tool; determining a processed error from the measured value obtained; and feeding a correction value produced on the basis of the processed error back to the NC machine tool.
2. Description of the Related Art
A manufacturing system of feedback type has been known in the art, which measures a processed part on a work in a process line for determining its processed error and alters a process condition for a NC machine tool based on the processed error (for example, JP 5-224715A). Such the manufacturing system of feedback type is directed to substantially alter the process condition on the basis of a dimensional processed error at the processed part and information of its variation trend obtained during or after processing. Therefore, it is advantageously capable of improving and maintaining a process precision for a component by feeding back a measured result in real time.
Methods of correcting the process condition in such the system have been proposed, which include a method of producing a re-process program for modification processing (for example, JP 3-176703A) and a method of correcting a correction value described in a process program (for example, JP 3-202252A).
The above-described conventional process systems are, however, all designed to add a certain process condition alteration to the process program for controlling the NC machine tool. Therefore, they have difficulties in processing to alter the process program and in controlling timings for alteration disadvantageously. In particular, modifications of process conditions for a plurality of NC machine tools require an independent modification of the process condition every machine tool. This causes a problem to complicate an algorithm for modifying the process conditions.
The present invention has been made in consideration of the above situation. The present invention accordingly has an object to provide a manufacturing system and method capable of smoothly modifying a process condition for a NC machine tool in such a manufacturing system that modifies the process condition thorough a feedback of a processed result by the NC machine tool.
The present invention is provided with a manufacturing system, which comprises a NC machine tool for processing a work in accordance with a process program having a process condition. It also comprises a measuring device for measuring the work processed by the NC machine tool, and a process condition correcting means for modifying the process condition of the process program on the basis of a measured result from the measuring device. The process condition modifying means includes a correction data file producing means for producing a correction data file to modify the process condition on the basis of the measured result from the measuring device. The correction data file has variables capable of being referred directly or indirectly from the process program. The variables each store a correction value for each processed part. The process condition modifying means also includes a correction data file storage means for storing the correction data file produced at the correction data file producing means. The process condition modifying means further includes a correction data file transferring means for transferring the correction data file stored in the correction data file storage means to the NC machine tool prior to the NC machine tool processing the work. The NC machine tool modifies the process condition with reference to the correction values stored in the variables in the transferred correction data file in accordance with the process program.
The present invention is also provided with a manufacturing method, which comprises the step of NC-processing a work by a NC machine tool operable in accordance with a process program having a process condition. It also comprises the steps of measuring the work processed in the step of NC-processing, and of modifying the process condition of the process program on the basis of a measured result obtained from the step of measuring.
The step of correcting the process condition includes the step of producing a correction data file to modify the process condition on the basis of the measured result. The correction data file has variables capable of being referred directly or indirectly from the process program. The variables each store a correction value for each processed value. The step of correcting the process condition also includes the step of storing the correction data file produced in the step of producing. It further includes the steps of transferring the correction data file stored at the step of storing to the NC machine tool prior to the NC-processing, and of modifying the process condition contained in the process program by referring the transferred correction data file in the process program.
According to the present invention, the correction data file is produced on the basis of the measured result. The correction data file is then transferred to the NC machine tool. The process program in the NC machine tool alters the process condition with reference to the correction data file. Therefore, the process program itself has no need to be altered. In addition, reference to the correction data file is performed in the process program in the NC machine tool. Therefore, it is sufficient to transfer the correction data file to the NC machine tool previously or to put it in a readable state from the NC machine tool. Thus, the production of the process program can be very easily achieved as well as the transferring control for the correction data.
A timing of reading the correction data file in the NC machine tool can be controlled by, for example, describing an instruction for reading the correction data file in the process program for the NC machine tool followed by decision and process instructions of the process condition. The correction data file transferring means may also output an acceptance request for the correction data file to the NC machine tool. In this case, it transfers the correction data file to the NC machine tool after receiving an acceptance message from the NC machine tool. The former is particularly suitable for an off-line process system and the latter particularly for an in-line process system.
The process program for the NC machine tool may include a process main program and a correction macro program. The process main program comprises the steps of reading in the correction data file and reading out the correction macro program on decision of the process condition per each processed part. The correction macro program comprises the step of computing a correction value for the process condition on the basis of the read in correction data file and storing the correction value into a variable capable of being referred from the process main program.
The correction data file producing means may act a predetermined range from a limit value of a design tolerance for each processed part as a correction range. It may store an error component relative to a nominal as a correction value in the correction data file if the measured result from the measuring device is contained within the correction range.
The correction data file producing means may store a value for activating an abnormal process in an alarm variable capable of being referred from the process program and may describe the alarm variable in the correction data file if an error between the measured result from the measuring device and a nominal is equal to a predetermined multiple of a designated tolerance. The NC machine tool may execute a predetermined abnormal process if the value for activating an abnormal process is stored in the alarm variable described in the correction data file.